可變容積式共鳴消音器之設計

Abstract

本研究的目的旨在解決廠房排氣管路噪音的問題，因此設計出一可變容積式共鳴消音器，希望藉由共鳴腔的長度改變來控制排氣管出口端的最大消音頻率。這個最大消音頻率也就是共鳴腔的共鳴頻率，其值由共鳴腔規格所決定。由於該頻率之噪音能量已被共鳴腔所吸收，因此在出口端之噪音值會有明顯的下降。 經實驗證實，共鳴腔容積改變會導致其共鳴頻率隨之改變。其容積越大，則共鳴頻率越小；反之，容積越小，則共鳴頻率越大。共鳴容積之長度在60 mm、80 mm、100 mm、200 mm、300 mm、400 mm與500 mm時所對應的共鳴頻率分別為2,004 Hz、1,764 Hz、1,544 Hz、1,272 Hz、1,148 Hz、1,020 Hz與880 Hz。依照這個概念，可以在不需大幅改變原有通風系統的排氣管路下，設計出能夠抑制某個低頻噪音的消音器。

The purpose of this study is to solve the problem of exhaust pipe noise in the factory. By changing the length of the resonant volume, in order to control the maximum noise reduction frequency at the end of the pipe, a variable volume resonant muffler was designed. This maximum noise reduction frequency is in fact the resonance frequency, and depends on the size of the resonant volume. It seems to be that the resonance frequency noise decreases at the end of the pipe when the resonant volume absorbs its energy. Under experimentation, different resonant volumes will change the resonance frequency. The bigger the volume, the lower the frequency, and on the contrary, the smaller the volume, the higher the frequency. When the lengths of the resonant volume are 60 mm,80 mm,100 mm,200 mm,300 mm,400 mm and 500 mm, the resonance frequency are 2004 Hz,1764 Hz,1544 Hz,1272 Hz,1148 Hz,1020 Hz and 880 Hz. According to this concept, a muffler can be designed to confine a wanted low frequency noise without largely changing the original exhaust ventilation system.